Equipment and technology for hardening of roll surfaces, including point switch cores

Away back in the sixties many researchers observed the effect of hardened surfaces in the process of electrohydropulse treatment of the later.

This method is about treatment of surfaces by pressure repeated pulses generated by high-voltage discharges in water. Thus, the treatable structure is also immersed in water. At repeated pulse loading plastic deformation occurs in surface layers of the treatable product. In material structure the increase in density of dislocations is observed, besides in steel structure the twins emerge, and also the structure is locally refined that results in by 40-50% enhanced hardness and by 25-30% increased wear-proof property of roll surfaces, and longer service life of products, respectively.

The research conducted by the specialists of Science and Technology Center "VEGA" of the Institute of Pulse Processes and Technologies (STC "VEGA" of IPPT of NAS of Ukraine) jointly with JSC "Dnepropetrovsk Pointers Plant" showed that after electrohydropulse treatment of roll surfaces of point switches (frogs) the roll surfaces were hardened, namely the hardness index НВ raised from 210-220НВ to 300-310НВ, and their service life increased by 30%, respectively.

Thus, as the researches have shown, at electrohydropulse effect applied for materials, material microstructure influence on a hardening process is described by the same laws, as for other types of pulse and shock treatment.

The advantages of electrohydropulse treatment technology:

  • Productivity increase;
  • Radical improvement of sanitary-and-hygienic working conditions;
  • Liquidation of manual labor and sharp decrease in occupational diseases;
  • Liberation of production premises floor spaces and environmental problems solving.

In the near future the specialists of STC "VEGA" are planning to develop documentation for the electrohydropulse plant used to harden the point switch cores having the following parameters:

Number of point switch frogs treated simultaneously, pcs. 1
Productivity at point switch frog treatment, pcs/h 1,5
Maximum sizes of treatable products (length х width х height), mm 3750x600x300
Consumed power, kW, no more than 300
Occupied area, m2, no more than 70

 

These plants are operated as follows.

The parts to be treated are loaded by workshop load-lifting tools on a raising platform being in a loading position, then the platform with the parts sinks in the technological bath filled with water. The working electrode is supplied to the parts and fixed in the set point of treatment, the high-voltage electric equipment switches on, thus starting the treatment, providing strengthening of treatable surfaces. The working electrode is moving along intended trajectory.

Processes of electric power accumulation, maintenance of a working interval "electrode-part" are carried out automatically. Upon termination of treatment working electrodes are taken away outwards the bath, the platform is hoisted to the unloading position, and on the other side of the plant a new platform with untreated parts goes for treatment. The cycle repeats.

The plants operate in manual and semi-automatic modes and they are controlled by a remote control panel.

Our specialists from the Science and Technology Center "VEGA" render their assistance to the Clients in mounting, adjustment and commissioning of EH plants, consult on the issues concerning the technology of electrohydraulic treatment of the parts taking into account their specific features and range, train the service personnel, perform warranty and post-warranty service of the equipment. For specific orders STC "VEGA" at IPPT can develop a special design project of EHP proceeding from the Client’s local conditions (product range, available buildings, etc.).

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